Abstract
Purpose: :
To describe and characterize histiocytic sarcoma in the eyes of dogs.
Methods: :
Cases diagnosed as histiocytic sarcoma were selected from the Comparative Ocular Pathology Laboratory of Wisconsin database. Slides were reviewed to describe the cellular morphology, localize the tumor within the globe, record the tumor distribution and measure the size of the tumor. Further sections were taken to perform immunohistochemistry for Melan–A, CD–18 and S–100, and for ferric iron staining. The following clinical information was recorded: breed, sex, gender, laterality, clinical signs upon presentation and follow–up information.
Results: :
Twenty–six cases were confirmed as being histiocytic sarcoma according to the immunohistochemical results (CD–18 positive and Melan–A negative). The most prevalent breed was Rottweiler (8 cases), followed by Retriever breeds (7 Golden and 5 Labrador). The mean age was 8.61±2.43 years. There were 3 intact males, 8 castrated males, 1 intact female and 14 spayed females. In 15 dogs there were no concurrent systemic clinical signs at the time of diagnosis. Fifteen dogs died due to causes related to the tumor, although only 3 of them received a necropsy. Survival time varied between 5 days and 6 months after enucleation. Three of the dogs were alive at the time the information was gathered. In 8 cases no follow–up information was obtained. Mean surface of tumor was 0.613±0.38 cm2. S–100 was diffusely positive in 10 cases, isolated positive cells were found in 11 cases and 5 cases were completely negative. Seven of the cases were positive for ferric iron and the remaining (19 cases) were negative for this staining.
Conclusions: :
Histiocytic sarcoma must be considered in the differential diagnosis of dogs with intraocular masses, especially in Rottweilers and Retriever breeds. Because it carries poor prognosis, it must be distinguished from melanoma. A good discriminator for this purpose in paraffin–embedded tissues is finding CD–18 positive cells and no reactivity against Melan–A. S–100 and ferric iron staining do not seem to be useful.
Keywords: tumors • immunohistochemistry